machine roomless elevator
One or more gearless traction elevators where the lift mechanism fits entirely within the hoistway.
A machine roomless elevator is a gearless traction elevator with a technologically advanced design permitting the entire lift mechanism (including the sheave) to fit within the elevator shaft or hoistway. Because this eliminates the need for an elevator penthouse on an extra floor level, it reduces construction costs, saves space, and can improve architectural flexibility by permitting a flat roof.
This feature can be assigned to a built object when at least one machine roomless elevator is present. It does not mean that all elevators within the structure have to be machine roomless, although that often is the case.
The defining arrangement places the lift mechanism within the shaft or hoistway of the gearless traction elevator. It is the machinery arrangement, rather than a particular roof shape, that identifies this feature; at least one such elevator is sufficient for the building to have it.